(MOdulator-DEModulator) Until the late 1990s, the term referred to a device that allows a computer or terminal to transmit data over a standard dial-up telephone line. Since the advent of cable and DSL connections, the term may also refer to high-speed broadband modems (see cable modem, DSL and cellular modem).
This definition pertains only to dial-up modems, also known as "analog modems," which convert digital pulses from the computer to audio tones that analog telephone lines can carry, and vice versa. V.92 is the last dial-up standard, providing a data rate of 56 Kbps (see V.92).
New computers geared for home users may or may not have a built-in analog modem, while those targeted for the office typically do not. However, a modem can be added internally via a PCI card, or externally via a USB port.
Like a Telephone
A modem dials the line and answers the call. It performs the digital-to-analog and analog-to-digital conversion while controlling transmission speed. Whatever the top speed, some number of lower speeds are also supported to accommodate old modems or negotiate downward on noisy lines. Over the years, speeds evolved from 300 bps to 56 Kbps.
Error Correction and Compression
Modems have built-in error correction (V.42) and data compression (V.42bis, MNP 5). On files that are already compressed, the hardware data compression adds little value, because it cannot make compressed files smaller. Modems also have automatic feature negotiation, which adjusts to the other modem's speed and hardware protocols.
The Hayes Standard
Most modems use the Hayes AT command set, which are machine instructions for modem control. The term modem has been used as a verb; for example, "I'll modem you later." See modem status signals and AT command set.
The Sportster
The Sportster was one of the hottest-selling products in the 1990s as people went online in record numbers. External units have the advantage of status lights, which help troubleshoot connections. Internal modems have since become the norm. (Image courtesy of 3Com Corporation.)
A Rack of Hayes Modems
Hayes was the pioneer in personal computer modems and set the standard for control commands. Hayes produced a full line of modems from singles to rack-mounted units such as this model with 16 modem cards. Allowing card replacement with power on, rack-mounted modems like these are found by the thousands at large ISPs. (Image courtesy of Hayes Microcomputer Products, Inc.)
This definition pertains only to dial-up modems, also known as "analog modems," which convert digital pulses from the computer to audio tones that analog telephone lines can carry, and vice versa. V.92 is the last dial-up standard, providing a data rate of 56 Kbps (see V.92).
New computers geared for home users may or may not have a built-in analog modem, while those targeted for the office typically do not. However, a modem can be added internally via a PCI card, or externally via a USB port.
Like a Telephone
A modem dials the line and answers the call. It performs the digital-to-analog and analog-to-digital conversion while controlling transmission speed. Whatever the top speed, some number of lower speeds are also supported to accommodate old modems or negotiate downward on noisy lines. Over the years, speeds evolved from 300 bps to 56 Kbps.
Error Correction and Compression
Modems have built-in error correction (V.42) and data compression (V.42bis, MNP 5). On files that are already compressed, the hardware data compression adds little value, because it cannot make compressed files smaller. Modems also have automatic feature negotiation, which adjusts to the other modem's speed and hardware protocols.
The Hayes Standard
Most modems use the Hayes AT command set, which are machine instructions for modem control. The term modem has been used as a verb; for example, "I'll modem you later." See modem status signals and AT command set.
The Sportster
The Sportster was one of the hottest-selling products in the 1990s as people went online in record numbers. External units have the advantage of status lights, which help troubleshoot connections. Internal modems have since become the norm. (Image courtesy of 3Com Corporation.)
A Rack of Hayes Modems
Hayes was the pioneer in personal computer modems and set the standard for control commands. Hayes produced a full line of modems from singles to rack-mounted units such as this model with 16 modem cards. Allowing card replacement with power on, rack-mounted modems like these are found by the thousands at large ISPs. (Image courtesy of Hayes Microcomputer Products, Inc.)
 | Reproduced with permission from Computer Desktop Encyclopedia. Copyright (c) 1981-2009 The Computer Language Company Inc. All rights reserved. |
Additional Resources
- sMonitor 4.2 build 1501 (Windows)
- sMonitor is a network monitoring software that allows you to verify the network connectivity of TCP/IP hosts on the Internet and LAN. The built-in NT service periodically pings, or checks TCP and UDP ports on network devices.If the destination host fails to reply to a ping, connection request, or user...
- Software downloads 2009-11-28
- Did you pick up any Black Friday deals?
- Reane it "Black Death" and I still wouldn't go out there...A $300 netbook on sale for $200, using $50 worth of parts, and doesn't perform as a good as something made for 2 cents... that's no deal.Stores carry a limited number of items reduced slightly more than usual, hype...
- Discussion threads 2009-11-27
- HP Pavilion dv4-2045dx
- Editors' note: This review is part of our 2009 Retail Laptop and Desktop Holiday Roundup, which covers specific fixed configurations of popular systems found in retail stores.The HP Pavilion dv4-2045dx offers more multitasking muscle than many of the other mainstream budget retail laptops we've recently reviewed. Helped by a 7,200rpm...
- Product reviews 2009-11-24
- Apple ads dodge the network coverage issues
- Misleading advertising is in Apple's DNAWhy would their carrier be otherwise?RE: Apple ads dodge the network coverage issuesI saw the "What time's the movie" add last night. In the real world, it would not play out the way it is shown. The fine print at the end of...
- Discussion threads 2009-11-24
- Phone Amego 1.1.2 (Mac)
- Phone Amego provides Caller ID, Address Book, Google Voice, and Bluetooth phone integration in Leopard and beyond. Features: On screen caller ID with optional voice announcement Dial calls directly from your Address Book or selected text Create an Address Book contact from received caller ID with one click ...
- Software downloads 2009-11-24
- iData 3.1.9 (Mac)
- iData 3 is an easy-to-use database application for storing text and graphics. Provides several ways to retrieve and view your information. Is very flexible and user-configurable.Synchronizes datafiles to iData Mobile on the iPhone Stores data in either freeform or user-defined field-based formats. Can "grab" and store Web page addresses and...
- Software downloads 2009-11-24
- Magic Translator 8.12 (Windows)
- Magic Translator is a multilingual translation software based on Internet resources. There now exists many distributed machine in the world that can do the language translation work from a certain language to another specified language. Can we exploit these free or public domain resources? Magic Translator could be the answer....
- Software downloads 2009-11-24
- Throttle 6.11.23.2009 (Windows)
- Throttle is a tool for all that allows you to modify your modem settings to increase internet performance up to 200% or higher. No modifications to your hardware are made and all adjustments and settings are done in an easy to use interface that a child could use. Most other...
- Software downloads 2009-11-23
- MobileVT 4.0 (Mobile)
- Terminal emulator for Windows Mobile Pocket PC. Emulates telnet, vt102, vt100, vt52, ssh and ansi terminals; connects using network adapter, modem, serial port also bluetooth and Ir types; transfers files with xmodem, zmodem and scp protocols. Features a customizable colour display that can be scrolled using standard scrollbars or dragging...
- Software downloads 2009-11-23
- Live from Googleplex: Chrome OS details revealed
- Ubuntu 9.10 has more immediate potentialMight I suggest trying Ubuntu 9.10? A phenominal OS with much more to offer then even Windows 7.Open source, free and ready to try today...http://blogs.techrepublic.com.com/10things/?p=1122http://www.tuxradar.com/content/vista-windows-7-ubuntu-904-and-910-boot-speed-comparisonhttp://www.youtube.com/watch?v=lYgWE6Svpaghttp://www.youtube.com/watch?v=16-nad9N3pgNot that I have readI'd stick with 904immediate potential to sink in obscurityGoogle was Linux's last fleeting chance to turn...
- Discussion threads 2009-11-19
- FAA hit with network glitch; Flight plans go manual
- Another glitch with a linux network? Its hard to believe people still use it for anything critical like the FAA and flight tracking. Its a toy OS and should not be used when the lives of people are dependent upon it.Cisco supplies the network backboneIt will be interesting to see...
- Discussion threads 2009-11-19
- AOL/Facebook in the Enterprise
- In 1994 America Online trailed Compuserve and Prodigy, a third subscription option in how you hooked your modem up to the internet to go cyber surfing. What propelled AOL to global dominance by the end of that decade was their proprietary 'rainman' platform, which enabled partners...
- Blog posts 2009-11-18
- cFosSpeed 5.0 (Windows)
- Internet Acceleration with Traffic Shaping and bandwidth management. Ping optimizer plus packet prioritization. Maximum Download and Minimum Ping. For DSL, ADSL, VDSL, Cable, Modem, ISDN, Mobile (GSM, GPRS, HSCSD, UMTS, HSDPA), Filesharing (P2P), Online Games, VoIP, Streaming Media and Tuning. Version 4.50 build 1456 adds new skin: "LC History", adds...
- Software downloads 2009-11-18
- FaxAmatic 09.11.13 (Windows)
- "Send and Receive fax with single computer and modem or network with multiple modems. FaxAmatic will add a fax generating print driver to your system, giving you the ability to generate a fax from any document and send to any fax machine in the world. Popular with oil companies. The...
- Software downloads 2009-11-17
- MacWise 11.71 (Mac)
- MacWise emulates ADDS Viewpoint, Wyse 50, Wyse 60, Wyse 370, Televideo TV 925, DEC VT100 and Prism terminals. Esprit III color is also supported in Wyse 370 mode.MacWise allows a Macintosh to be used as a terminal -- connected to a host computer directly or via modem. The emulators support...
- Software downloads 2009-11-16
- Aluratek WMQ137AM 3G Wireless USB/PCMCIA Cellular Router - Retail
- Aluratek 3G USB/PCMCIA routerIt's probably my error, but I can't get any of three computers to see the Aluratek router and Aluratek does not respond to support questions. I can't say if it works with my ZTE USB modem since it will not install. I bought it in Texas and...
- Discussion threads 2009-11-15
- Gateway NV7802u
- Editors' note: This review is part of our 2009 Retail Laptop and Desktop Holiday Roundup, which covers specific fixed configurations of popular systems found in retail stores.Gateway continues to offer some of the best bang-for-your-buck retail laptops. The NV7802u is a fine example: It's a 17-inch wide-screen model with a...
- Product reviews 2009-11-13
- The stupid network will get a hearing
- Leave my bits aloneIf I pay for unlimited service up to a certain speed that's what I expect to get. The fee I pay is supposed to cover the level of service I order. If a company is investing in a service I didn't buy, they neeed to get their...
- Discussion threads 2009-11-13
- launch2net 1.8.8.8 (Mac)
- Attach, click, connect launch2net is a mobile connection manager. With launch2net, you can use your mobile device like a mobile phone, ExpressCard, PC datacard or USB modem to connect your Mac to the Internet in one easy step. The powerful configuration assistant automatically detects your mobile device and configures...
- Software downloads 2009-11-13
- Token2Shell 5.4 (Windows)
- Token2Shell supports all the widely used algorithms and methods for an SSH connection. Once Token2Shell is installed, simply type your server address and hit 'Enter'. Along with robust SSH features, Token2Shell also supports TELNET, TCP Direct, SerialCOM Port and ModemPhone connections. Token2Shell also includes a dedicated standalone application for SSH...
- Software downloads 2009-11-12
Neighboring Terms
Premier Vendor Content Whitepapers, webcasts & resources from our Power Center Sponsors
- New Online Dashboard for IT Leaders
-
Read about top issues IT decision-makers face every day, plus get cost-effective solutions to real-life IT problems.
- Learn more >>
- Reduce risk. Reduce complexity. Increase reliability.
-
A simplified IT environment isn't just less complex. It's also more reliable. Standardize on a single Linux platform with SUSE Linux Enterprise from Novell, and get the world's most interoperable Linux
- Learn more >>
- Save time with automated shipping solutions
-
The Business Essentials Guide provides you useful tools and templates to help grow your business and save you time with automated shipping solutions.
- Visit the UPS Business Essentials Guide
- Microsoft Dynamics CRM Online - Free Six-Month Trial for Eligible Organizations
-
Microsoft Dynamics CRM Online provides fast online access, simple contact management and better sales performance for a low monthly cost - the best value on the market today.
- Learn more about the free, six-month trial offer>>
Meet Doc
-
-
Here to help you with your Document Management Needs
- Check out Doc’s Blog on ZDNet
- Help your company, help the earth I want to share with you the Environmental Defense Fund Paper Calculator, which allows you to gauge your organization's environmental impact.
- Which is Greener: Paper or Digital? The Answer May Surprise You Anything we can do to reduce paper consumption is good. But what about the impact of digital waste?
-
Produced by
ZDNet and -
